Taxan derivatives are known as compounds having an antitumor activity (Patent References 1 to 3). Patent References 2 and 3 describe orally-administrable taxan derivatives and a method for producing such orally-administrable taxan derivatives. Patent References 2 and 3 describe a method for producing taxan derivatives where osmium tetroxide is used for the oxidation during the process (including the following Production Method 1 and Production Method 2, in which R1 represents a dimethylaminomethyl group or a morpholinomethyl group, R2 represents a halogen atom, or an alkoxy group having from 1 to 6 carbon atoms, R3 represents a hydroxyl group optionally having a protective group).
Production Method 1:
Production Method 2:

The method for producing the compound [b] from the compound [a], or the method for producing the compound [d] from the compound [c] comprises converting the terminal olefin of the compound [a] or the compound [c] into a diol by an oxidizing agent such as N-methylmorpholine-N-oxide in the presence of a catalyst of osmium tetroxide, then oxidatively cleaving them with sodium periodate or the like into an aldehyde, and reacting it with a corresponding amine to obtain the compound [b] or [d] (see Patent Reference 3, paragraphs [0058] to [0061]).    Patent Reference 1: JP-A-9-12578    Patent Reference 2: WO 01/27115    Patent Reference 3: JP-A-2002-332287